What is Obscenity?

Legal Definition
Crim. law. Such indecency as is calculated to promote the violation of the law, and the general corruption of morals.

2. The exhibition of an obscene picture is an indictable offence at common law, although not charged to have been exhibited in public, if it be averred that the picture, was exhibited to sundry persons for money. 2 Serg. & Rawle, 91.
-- Bouviers Law Dictionary
Legal Definition
The character or quality of being obscene; conduct tending to corrupt the public morals by its indecency or lewdness. State v. Pfenninger, 76 Mo. App. 313; In S. v. Loftis (D. C.) 12 Fed. 671.
-- Black's Law Dictionary
Legal Definition
A category of speech unprotected by the First Amendment.
Legal Definition
Indecency; that which tends to corrupt the morals.
-- Ballentine's Law Dictionary